1. Field of the Invention
The invention relates generally to methods and devices for heating or cooling viscous materials and particularly to methods and devices for producing food products from meat emulsions.
2. Description of Related Art
Methods for producing meat emulsions and foods from such emulsions are known in the food industry. Meat emulsions are widely used in the production of products such as bolognas, frankfurters, sausages, animal foods, and the like.
Typically, meat emulsion products are prepared by mixing, chopping, and emulsifying a mixture of raw meat materials such as lean skeletal beef and pork, meat by-products, ice, salt, spices, and curing salts. The resulting emulsion contains fine fat particles coated with protein from the meat ingredients. For a sausage product, the resultant meat emulsion is then stuffed into a suitable casing that serves as a processing mold. The casing is then heated at increasing temperatures, for example 55° C. to 77° C., for extended periods, which may vary between 1 to 8 hours or more, depending on the volume of meat emulsion being processed.
The heating of the meat emulsion causes the protein contained therein to coagulate or to set solid. This thereby entraps the fat particles in the protein matrix thereby forming a firm meat emulsion product. The resultant meat emulsion product is a uniform, homogeneous mass that contains no discrete particles of meat and retains the shape of the casing when set.
To reduce the cost of certain food products to consumers, there has been a demand, in recent years, for meat emulsion products that resemble chunks or pieces of natural meat in appearance, texture, and physical structure, i.e., meat analogs. Such products are used as a partial or complete replacement for more expensive natural meat chunks in food products such as stews, pot pies, casseroles, canned foods, and pet food products.
Chunky meat products are highly desirable in human and pet foods, both for aesthetic quality and consumer appeal. These chunky products provide a more economical product that attempts to simulate natural meat chunks in shape, appearance and texture. It is highly desirable that these products retain their shape, appearance, and texture when subjected to commercial canning and retorting procedures.
Efforts directed to providing such simulated natural meat chunks have included producing such products from vegetable protein sources, using extrusion-expansion techniques. Such products have met with some acceptance in the food industry, but they have been limited primarily to use as meat extenders. Products produced using vegetable protein sources in an extrusion-expansion procedure lack the appearance and texture of natural meat and therefore are generally not suitable as full substitutes for meat.
Similarly, meat extrusion products, based on meat protein, produced by conventional procedures have not been entirely satisfactory. These products are in the form of a uniform, homogeneous mass, and lack the structure, texture, and appearance of natural meat chunks. Therefore, these products are not suitable for use in applications in which the use of simulated meat chunks is desired.
The meat emulsion product is in the form of distinct chunks or pieces having a plurality of juxtaposed, manually separable meat-like layers resembling a chunk of natural meat in appearance, texture, and consistency. The meat emulsion chunks are suitable for use as a partial or complete replacement for more expensive natural meat chunks in both human foods and animal foods. They retain their integrity and shape when subjected to commercial canning and sterilization procedures such as those required in the production of retorted, high moisture food products.
Conventional concentric tube heat exchangers comprise cooling systems that obstruct the flow of viscous and/or fibrous products through the exchanger. This obstruction may change the property of the product, cause equipment clogging and reduce output. Similarly, increasingly long tubes are required to cool the product as needed. However, using multiple tube heat exchangers lead to increased clogging, uneven flow and low throughput between the tubes.